The present invention relates to a box making apparatus and more particularly to a unique device for squaring folded boxes of corrugated material.
Various types of equipment are used to manufacture corrugated paperboard boxes or cartons. The equipment includes printers, rotary die cutters used for slotting and scoring and folder/gluers. Typically, blanks of corrugated paperboard are slotted and score lines are formed. The paperboard blanks are then passed into a folder/gluer. The folder/gluer generally employs bars, belts or rollers to progressively fold the blank and apply glue to form a folded box or container having the shape of a flattened parallelogram. The folded blanks are then transported to a counter/ejector or accumulator device. The blanks are stacked, counted and ejected in bundles. Examples of such equipment may be found in U.S. Pat. No. 3,850,085 entitled METHOD AND APPARATUS FOR FABRICATING AN ELONGATED CARTON, which issued on Nov. 26, 1974 to Clemm; U.S. Pat. No. 3,992,982 entitled FOLDING APPARATUS FOR CORRUGATED PAPERBOARD BLANKS, which issued on Nov. 23, 1976 to Huiskes; U.S. Pat. No. 4,041,849 entitled APPARATUS FOR FOLDING CARTON SHEET, which issued on Aug. 16, 1977 to Tsukasaki; and U.S. Pat. No. 4,254,692 entitled HELICAL FOLDER FOR PAPERBOARD BLANKS, which issued on Mar. 10, 1989.
The flat folded boxes are often out-of-square when they leave the folder/gluer. Inherent design and operational problems, such as belt slippage and drag on the folding bars, will produce a folded box wherein the flaps fold in a skewed or out-of-square manner. The stacks of folded boxes can be subjected to an edge beating or "spanking" action in the counter/ejector or other accumulator to correct the out-of-square condition. Spanking the folded boxes while the glue is still wet will square the folded container blanks in the stack. A spanker mechanism, however, generally works only if the boxes are slightly skewed.
Heretofore, it has been proposed to use twisted belts driven by variable speed motors in an attempt to correct skewness and slot gap error. The twisted belts are typically mounted close to the folding crease of the boxes. Consequently, the belts have a limited mechanical advantage for correcting skewness in gap area. Such an arrangement has only limited utility. The box flaps, upon leaving the folding section and entering the counter/ejector, are immediately caught in the nip of the feed rollers of the counter/ejector. The rollers prevent the box flaps from shifting since they have greater gripping strength than the twisted belts. The rollers, therefore, negate the effort of the twisted belts to make any correction in the out-of-square condition. A conflict, therefore, exists between the powered, variable speed twisted belts at the end of the folding section of the apparatus and the fixed speed rollers at the entrance of the counter/ejector.
Examples of prior devices which address the out-of-square condition may be found in U.S. Pat. No. 3,744,649 entitled SQUARING AND BUNDLE COUNTING MACHINE, which issued on Jul. 10, 1973 to Ward, Jr. and U.S. Pat. No. 4,976,672 entitled SQUARING FOLDED CONTAINER BLANKS, which issued on Dec. 11, 1990 to Harrison et al.